How to determine a bolt pattern

To find the bolt pattern on a car you would need to measure the diameter of a
circle drawn through each lug stud. On cars with an even number of lugs all that
is necessary is to measure the distance from the center of one lug stud to the
center of the lug stud directly opposite. On cars with an odd number of lug
studs it becomes a bit more involved. However we have a relatively simple
solution to solve this. You need to measure the distance from the center of a
lug stud to the outside of an opposing lug stud (see diagram). This will give
you a relatively accurate bolt circle diameter.